Changes in soft tissue elasticity are usually related to pathological processes. Because of this, palpation is still widely used for diagnosis. Its efficacy, however, is limited to abnormalities located relatively close to the skin surface. The goal of quantitative elasticity imaging is to develop surrogate, remote palpation, thus expanding its range to include deep lying lesions. The elastic properties of any continuous medium such as tissue can be assessed through precise measurement of mechanical deformations throughout that medium induced by forces applied at the surface. Using modern medical imaging devices to precisely measure internal motion, it should be possible to estimate and even image elastic properties of internal organs. In competition with other imaging modalities, ultrasound has two major advantages for elasticity imaging; it is inherently real-time and speckle artifacts limiting the quality of conventional images provide excellent markers for accurate tracking of tissue motion. Elasticity can be imaged, therefore, by measuring motion with an ultrasound speckle tracking algorithm, followed by reconstruction of the elasticity distribution. Although some other imaging systems, particularly real- time ultrasound, must be used to monitor tissue motion, elasticity imaging represents a fundamentally new diagnostic modality. To investigate quantitative elasticity imaging for medical diagnosis, a research plan addressing the important clinical problem of renal inflammation and scarring has been formulated. Preliminary data support the hypothesis that kidney elasticity changes with renal damage and concomitant scarring before renal problems are detectable by traditional diagnostic techniques such as laboratory measurements of renal function. Therefore, quantitative elasticity imaging may be valuable in detecting and quantifying scar for conditions such as kidney transplant rejection where rejection is difficult to quantify from functional measurements alone. Based on the results of these studies, it is the long range goal of this research program to develop a sensitive diagnostic technique based on quantitative elasticity imaging permitting surrogate palpation of deep lying lesions.